Browse Topic: Hydraulic motors
Rolling bearings with optimized friction and performance characteristics can have a significant influence on reducing the power loss, design envelope and weight of hydraulic motors and pumps, gearboxes and axles in construction machinery. If correctly designed, rolling bearings can make a significant contribution to reducing carbon dioxide emissions. Most construction machinery is still operated conventionally, using diesel engines and hydraulic components. In the widely used adjustable axial piston pumps and motors, the input and output shaft are usually supported by two tapered roller bearings that are adjusted against each other. When designing the bearing support, it is advisable to reduce the preload to precisely the required minimum allowed by the load spectrum. The lower bearing preload leads to permanently lower axial forces between the tapered roller end face and inner ring rib and, therefore, to a corresponding reduction in frictional torque.
This SAE Standard applies only to new winches which are primarily designed for intermittent pulls and lifts and whose configuration and condition are the same as when they were shipped by the manufacturer. They are not intended to be used in any manner for the movement of personnel. They may be driven by any power source recommended by the manufacturer and will be capable of being powered in either direction. They will be equipped with an automatic safety brake system to control a load when lowering under power and positively hold a load when power is not being delivered to the winch. A hydraulic flow control valve or similar device may be used in the brake system to control a load when lowering under power. A clutch to release the drum for “free-spooling” may be provided and will be designed not to disengage itself under load. A drag brake may be provided to control “free-spooling,” but will not be relied on to control or hold a load. Power sources, such as hydraulic motors, even though they may be supplied or recommended by the winch manufacturer, are not considered a part of the winch so far as this document is concerned, except to whatever extent they are a part of the brake system.
The cooling system with two fans is generally driven by electrical motors in the small cars. Compared with the traditional cars, heavy duty trucks have the larger heat dissipation power of cooling system. The motors power consumption of dual fans will be larger and the two electrical motors will occupy a large space in the engine cabin. Hydrostatic drive refers to the cooling fan is driven by hydraulic motor, but it has the low transmission efficiency. According to the engine water temperature value and the actual working status of the hydraulic system, the actual speed of cooling fan can be controlled by the computer, which guarantees the normal working water temperature of the engine. Hydrostatic drive is generally applied to heavy vehicles, engineering machinery and excavators as driving source of cooling fan which contains the advantages of large output power, overload protection, continuous speed regulation and flexible space arrangements. Integrating the characteristics of the driving modes with the hydraulic motor and electrical motor, the two motors of cooling fan can adopt cooperative operation using both driving modes. In the situation of low heat dissipation power, the cooling fan only can be driven by electrical motor, and two motors work cooperatively when the engine have the high heat dissipation power. By means of establishing the fuzzy control strategy, the rotary speed of two motors can be adjusted according to the real-time engine water temperature variation. Compared with the conventional PID control, the fuzzy control can avoid overshoot and improve temperature control precision. Owning to the overflow loss of hydraulic valve, the performance analysis of two driving modes with two hydraulic motors and the dual electro-hydraulic motors will have a comparison. The results prove that the power consumption of pure hydraulic system is 5.3kW while the power consumption using dual electro-hydraulic motors is 3.5kW, so that the power consumption saves 34% on average.
In this paper a new pressure control method of a modified accumulator-type Electro-hydraulic Braking System (EHB) is proposed. The system is composed of a hydraulic motor pump, an accumulator, an integrated master cylinder, a pedal feel simulator, valves and pipelines. Two pressurizing modes are switched between by-motor and by-accumulator to adapt different pressure boost demands. A differentiator filtering raw sensor signal and calculating pedal speed is designed. By using the pedal feel simulator, the relationship between wheel pressures and brake force is decoupled. The relationships among pedal displacement, pedal force and wheel pressure are calibrated by experiments. A model-based PI controller with predictor is designed to lower the influences caused by delay. Moreover, a self-tuning regulator is introduced to deal with the parameter’s time-varying caused by temperature, brake pads wearing and delay variation. To verify the controller validity, a Rapid Control Prototype (RCP) test environment based on dSPACE is built. Self-designed HCU and pedal feel simulator are installed in test bench. The close loop test results of pressure tracking are plotted and analyzed by contrasting normal PI controller and proposed controller. The conclusion indicates that the proposed controller can reach a balance of rapidity and accuracy, meanwhile the operating time and energy consumption are also reduced.
The heavy duty trucks have large engine power and drive continuously in mountainous area, so the heat dissipation of engine is very important. In the traditional cooling system with fixed transmission ratio fan, the cooling capacity is insufficient and the engine is easy to be over-heated when the engine is working in low speed and heavy load conditions. Owning to the bigger size of electric motor compared to the hydraulic motor, it is not suitably applied to the heavy duty trucks. Contrasted with the electric motor, the hydraulic drive cooling system is widely applied in heavy duty trucks due to smaller size, larger power, continuous speed modulation and flexible installation location. However, the low transmission efficiency of the pump-motor system results in high power consumption of the cooling system. In this paper, the mathematical and simulation model of hydraulic-driven fan cooling system is established for the specific engine. The study applies the digital PID controller of continuous system to control the fan. The control algorithm of anti-integral saturation is compared with the conventional method. The results show that during the time progress of 700s, the mean power consumption with anti-integral algorithm respectively reduce by an average of 40.8%, 35.1% and 29.2% in the target temperature of 363.15K, 364.15K, and 365.15K compared with the traditional control method. Moreover, the PID control with anti-integral algorithm can improve the temperature control accuracy and effectively avoid the excessive cooling.
It is important for engineering firms to be able to develop forecasts of recommended courses of action based on available information. In particular, engineering firms must be able to assess the benefit of performing information-gathering actions. For example, an automobile manufacturer may use a computer simulation of a hydraulic motor and pump in the design of a new vehicle. The model may contain random variables that can be more accurately determined through expensive information-gathering actions, e.g., physical experiments, surveys, etc. To decide whether to perform these information-gathering actions, the automobile manufacturer must be able to quantify the expected value to the firm of conducting them. However, the cost of computing the expected value of information (through optimization, Monte Carlo sampling, etc.) grows exponentially with the amount of information that is to be gathered and can often exceed the cost of actually gathering the information. Thus, if information decisions are to be addressed algorithmically, there exists a need for novel algorithmic approaches to reduce the computational expense associated with computing the expected value of gathering information. The contribution of this paper is a novel algorithmic approach for approximating the expected value of perfect information (EVPI) for engineering design problems. In this research, we propose to recast the EVPI as a “parametric” problem. The value of recasting the problem is an exponential reduction in the computational complexity. The proposed approach is validated against a Monte Carlo sampling based approach, the traditional approach for solving EVPIs, on an engineering problem. The engineering problem is to compute the expected value of performing physical experiments to gather information about random variables in a computational model the efficiency of an engine and transmission. The results are compared in terms of computational expense and solution accuracy. The results indicate that by recasting the EVPI as a parametric problem the computational expense is reduced drastically while maintaining solution accuracy.
Nowadays, off-highway vehicles enjoyed a significant status in the national defense and civil construction. There is no doubt that the working conditions of off-highways are quite different from the conventional passenger cars, hence, their suspensions are particularly designed. Since the hydro-pneumatic suspension technology is maturely applied in engineering machinery, this paper presents a concept for a novel energy-harvesting device, which is applied in off-highway vehicles based on hydro-pneumatic suspension, namely, electro-hydraulic energy-harvesting suspension (EHEHS). The EHEHS took the fundamental of mechanism-electronic-hydraulic system, which consisted the following elements: a cylinder, 2 check valves, a hydro-pneumatic spring, a hydraulic motor, a DC motor, a processing circuit and a battery. In the EHEHS system, the cylinder is used to transmit the vibration energy into hydraulic energy, which is stored in hydro-pneumatic spring. The hydraulic motor is the energy conversion device that could translate the hydraulic energy into rotational kinetic energy, which could be converted into electric energy by the electric motor. The final electric energy is conserved in the battery after treatment by the processing circuit. Apart from the description of the configuration of the EHEHS, this paper also discuss the stiffness and damper characteristic of the novel energy-harvesting suspension by mathematic derivation, and a simulation based evaluation is present to show its application in an off-high way commercial vehicle.
Nearly 1000 university teams from 55 countries around the globe entered the first Valeo Innovation Challenge, the goal of which was to ‘design the product or system that will make the cars of 2030 smarter and more intuitive.’ THE UNIVERSIDADE FEDERAL DE MINAS GERAIS OF BRAZIL TOOK FIRST PRIZE, and a cash award of €100,000, in the first Valeo Innovation Challenge. Tying for second place and taking home €10,000 each were Canadian teams: the University of Ottawa and the University of Waterloo. The Brazilian team's project aims to reinvent the mechanical transmission system by coupling together the pump and the hydraulic motor. This innovation would enable the transmission to adjust to engine rpm continuously and automatically, thereby improving fuel efficiency and reducing CO2 emissions.
Due to the high demand of fuel efficient construction equipment, significant research effort has been dedicated to improving excavator efficiency. Among various possibilities, methods to recuperate energy during cab swing motion have been widely examined. Electric and hydraulic hybrids designs have shown to greatly improve fuel efficiency but require drastic design changes. The redesigned systems thus require many hours of operation to offset the manufacturing costs with fuel savings. In this research, a relatively simple swing energy recuperation system is presented using an additional accumulator, fixed displacement hydraulic motor, and control valves. With the system, hydraulic fluid is stored in an accumulator, and a simple controller opens a valve to allow the stored energy to assist the engine in running the main pumps. Using various accumulator capacity and hydraulic motor displacement combinations, the recuperation system was simulated for six cycles of a digging and dumping operation. The simulation results show that an optimum configuration reduces the swing energy consumption by 48% and the total excavator energy by 17% during digging and dumping operations.
This procedure will be generally applicable to three classes of hydraulic components as listed below:
Much of the available long-term storage test data has been reviewed and topically separated to enable the independent discussion of storage effects on fluids, seals, hydraulic components, and hydraulic systems. Comments are made in Section 4 concerning the applicability of the test results and regarding design practices for storability. Conclusions are drawn in Section 5 regarding inactive storage of hydraulic systems for at least a 7 year period.
Fluid pressure pulsation in a fluid system is an inherent consideration in applications such as aircraft engine and control systems where mechanical component fatigue life and flow performance are critical. Positive displacement pumps transmitting fluid through hydraulic lines under high pressure impart periodic flow pulses to the fluid which can induce undesirable pressure ripple. Some failures of advanced aircraft prototype hardware were traced to a break in the hydraulic component of the control system due to severe localized responses to periodic pressure pulsations produced by a pump flow-induced ripple at the system resonant frequency. This response is associated with a strong structural fluid resonance that is not sufficiently damped by fluid leakage internal to the aircraft hydraulic system. In the case of pumps or hydraulic motors the main source of pulsation energy is in the flow-induced pressure wave associated with the system plumbing pressure pulsations. The pressure wave may propagate in both the pumping wall and fluid as a result of fluid/structure coupling. For a high level of pressure pulsation, the resulting pumping wall motion can then cause mechanical fatigue and unwanted radiated noise and cavitation. This report describes the application of CFD analysis in an aircraft engine control system's vane pumps with a non-intrusive fluid wave in the system. The ultimate goal is to understand the root cause of the pressure pulses and to define improvements or corrective action.
The marine environment differs greatly from other environments in which hydraulics are used. This Recommended Practice provides hydraulic design considerations and criteria for the marine environment and is applicable to commercial vessels, military ships, and submersible vehicles. This document may be used for manned and un-manned vehicles.
In order to reduce fuel consumption, companies have been looking at hybridizing vehicles. So far, two main hybridization options have been considered: electric and hydraulic hybrids. Because of light duty vehicle operating conditions and the high energy density of batteries, electric hybrids are being widely used for cars. However, companies are still evaluating both hybridization options for medium and heavy duty vehicles. Trucks generally demand very large regenerative power and frequent stop-and-go. In that situation, hydraulic systems could offer an advantage over electric drive systems because the hydraulic motor and accumulator can handle high power with small volume capacity. This study compares the fuel displacement of class 6 trucks using a hydraulic system compared to conventional and hybrid electric vehicles. The paper will describe the component technology and sizes of each powertrain as well as their overall vehicle level control strategies. The fuel consumption will be evaluated on several driving cycles. The paper will then recommend specific powertrain configurations (i.e., hydraulic vs. electric hybrids) depending on specific driving conditions.
This SAE Standard describes a uniform method to calculate and specify travel performance characteristics of hydraulic excavators, material handlers, knuckle boom log loaders, delimbers, feller bunchers, harvesters, processors, and other knuckle boom material handlers. It establishes definitions and specifies machine conditions for calculations and tests. This document applies to crawler mounted machines such as hydraulic excavators as defined in SAE J/ISO 6165 and ISO 7135, and knuckle boom log loaders as defined in SAE J1209 and SAE J2055. This document also applies to certain forestry equipment defined in SAE J1209 and ISO 6814 that have crawler mountings such as delimbers, feller bunchers, harvesters, and processors. Included in the definition of hydraulic excavators are also front shovel, clamshell, and telescoping boom excavators.
This standard is applicable to off-road work machines - base machine and its equipment included in categories 1.1, 1.2, 2, 4, and 5 of SAE J1116.
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